Recent developer mistakes have involved accidentally committing quite large JAR files to repository history when they should have been taken from external binaries. Even if corrected in sources, the changesets continue to consume a lot of space in history that cannot be undone.
We should have a Mercurial hook preventing anyone from pushing any changeset containing a new or modified ZIP file. (Even if you need to store e.g. sample projects for tests, it is best to keep them unpackaged in the repo since that will compress much better and it is easier to follow modifications.)